// SPDX-License-Identifier: GPL-2.0
/*
 * Device driver for the Apple Desktop Bus
 * and the /dev/adb device on macintoshes.
 *
 * Copyright (C) 1996 Paul Mackerras.
 *
 * Modified to declare controllers as structures, added
 * client notification of bus reset and handles PowerBook
 * sleep, by Benjamin Herrenschmidt.
 *
 * To do:
 *
 * - /sys/bus/adb to list the devices and infos
 * - more /dev/adb to allow userland to receive the
 *   flow of auto-polling datas from a given device.
 * - move bus probe to a kernel thread
 */

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/sched/signal.h>
#include <linux/adb.h>
#include <linux/cuda.h>
#include <linux/pmu.h>
#include <linux/notifier.h>
#include <linux/wait.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/kthread.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>

#include <linux/uaccess.h>
#ifdef CONFIG_PPC
#include <asm/prom.h>
#include <asm/machdep.h>
#endif


EXPORT_SYMBOL(adb_client_list);

extern struct adb_driver via_macii_driver;
extern struct adb_driver via_cuda_driver;
extern struct adb_driver adb_iop_driver;
extern struct adb_driver via_pmu_driver;
extern struct adb_driver macio_adb_driver;

static DEFINE_MUTEX(adb_mutex);
static struct adb_driver *adb_driver_list[] = {
#ifdef CONFIG_ADB_MACII
        &via_macii_driver,
#endif
#ifdef CONFIG_ADB_CUDA
        &via_cuda_driver,
#endif
#ifdef CONFIG_ADB_IOP
        &adb_iop_driver,
#endif
#ifdef CONFIG_ADB_PMU
        &via_pmu_driver,
#endif
#ifdef CONFIG_ADB_MACIO
        &macio_adb_driver,
#endif
        NULL
};

static struct class *adb_dev_class;

static struct adb_driver *adb_controller;
BLOCKING_NOTIFIER_HEAD(adb_client_list);
static int adb_got_sleep;
static int adb_inited;
static DEFINE_SEMAPHORE(adb_probe_mutex);
static int sleepy_trackpad;
static int autopoll_devs;
int __adb_probe_sync;

static int adb_scan_bus(void);
static int do_adb_reset_bus(void);
static void adbdev_init(void);
static int try_handler_change(int, int);

static struct adb_handler {
        void (*handler)(unsigned char *, int, int);
        int original_address;
        int handler_id;
        int busy;
} adb_handler[16];

/*
 * The adb_handler_mutex mutex protects all accesses to the original_address
 * and handler_id fields of adb_handler[i] for all i, and changes to the
 * handler field.
 * Accesses to the handler field are protected by the adb_handler_lock
 * rwlock.  It is held across all calls to any handler, so that by the
 * time adb_unregister returns, we know that the old handler isn't being
 * called.
 */
static DEFINE_MUTEX(adb_handler_mutex);
static DEFINE_RWLOCK(adb_handler_lock);

#if 0
static void printADBreply(struct adb_request *req)
{
        int i;

        printk("adb reply (%d)", req->reply_len);
        for(i = 0; i < req->reply_len; i++)
                printk(" %x", req->reply[i]);
        printk("\n");

}
#endif

static int adb_scan_bus(void)
{
        int i, highFree=0, noMovement;
        int devmask = 0;
        struct adb_request req;
        
        /* assumes adb_handler[] is all zeroes at this point */
        for (i = 1; i < 16; i++) {
                /* see if there is anything at address i */
                adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
                            (i << 4) | 0xf);
                if (req.reply_len > 1)
                        /* one or more devices at this address */
                        adb_handler[i].original_address = i;
                else if (i > highFree)
                        highFree = i;
        }

        /* Note we reset noMovement to 0 each time we move a device */
        for (noMovement = 1; noMovement < 2 && highFree > 0; noMovement++) {
                for (i = 1; i < 16; i++) {
                        if (adb_handler[i].original_address == 0)
                                continue;
                        /*
                         * Send a "talk register 3" command to address i
                         * to provoke a collision if there is more than
                         * one device at this address.
                         */
                        adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
                                    (i << 4) | 0xf);
                        /*
                         * Move the device(s) which didn't detect a
                         * collision to address `highFree'.  Hopefully
                         * this only moves one device.
                         */
                        adb_request(&req, NULL, ADBREQ_SYNC, 3,
                                    (i<< 4) | 0xb, (highFree | 0x60), 0xfe);
                        /*
                         * See if anybody actually moved. This is suggested
                         * by HW TechNote 01:
                         *
                         * https://developer.apple.com/technotes/hw/hw_01.html
                         */
                        adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
                                    (highFree << 4) | 0xf);
                        if (req.reply_len <= 1) continue;
                        /*
                         * Test whether there are any device(s) left
                         * at address i.
                         */
                        adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
                                    (i << 4) | 0xf);
                        if (req.reply_len > 1) {
                                /*
                                 * There are still one or more devices
                                 * left at address i.  Register the one(s)
                                 * we moved to `highFree', and find a new
                                 * value for highFree.
                                 */
                                adb_handler[highFree].original_address =
                                        adb_handler[i].original_address;
                                while (highFree > 0 &&
                                       adb_handler[highFree].original_address)
                                        highFree--;
                                if (highFree <= 0)
                                        break;

                                noMovement = 0;
                        } else {
                                /*
                                 * No devices left at address i; move the
                                 * one(s) we moved to `highFree' back to i.
                                 */
                                adb_request(&req, NULL, ADBREQ_SYNC, 3,
                                            (highFree << 4) | 0xb,
                                            (i | 0x60), 0xfe);
                        }
                }       
        }

        /* Now fill in the handler_id field of the adb_handler entries. */
        for (i = 1; i < 16; i++) {
                if (adb_handler[i].original_address == 0)
                        continue;
                adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
                            (i << 4) | 0xf);
                adb_handler[i].handler_id = req.reply[2];
                printk(KERN_DEBUG "adb device [%d]: %d 0x%X\n", i,
                       adb_handler[i].original_address,
                       adb_handler[i].handler_id);
                devmask |= 1 << i;
        }
        return devmask;
}

/*
 * This kernel task handles ADB probing. It dies once probing is
 * completed.
 */
static int
adb_probe_task(void *x)
{
        pr_debug("adb: starting probe task...\n");
        do_adb_reset_bus();
        pr_debug("adb: finished probe task...\n");

        up(&adb_probe_mutex);

        return 0;
}

static void
__adb_probe_task(struct work_struct *bullshit)
{
        kthread_run(adb_probe_task, NULL, "kadbprobe");
}

static DECLARE_WORK(adb_reset_work, __adb_probe_task);

int
adb_reset_bus(void)
{
        if (__adb_probe_sync) {
                do_adb_reset_bus();
                return 0;
        }

        down(&adb_probe_mutex);
        schedule_work(&adb_reset_work);
        return 0;
}

#ifdef CONFIG_PM
/*
 * notify clients before sleep
 */
static int __adb_suspend(struct platform_device *dev, pm_message_t state)
{
        adb_got_sleep = 1;
        /* We need to get a lock on the probe thread */
        down(&adb_probe_mutex);
        /* Stop autopoll */
        if (adb_controller->autopoll)
                adb_controller->autopoll(0);
        blocking_notifier_call_chain(&adb_client_list, ADB_MSG_POWERDOWN, NULL);

        return 0;
}

static int adb_suspend(struct device *dev)
{
        return __adb_suspend(to_platform_device(dev), PMSG_SUSPEND);
}

static int adb_freeze(struct device *dev)
{
        return __adb_suspend(to_platform_device(dev), PMSG_FREEZE);
}

static int adb_poweroff(struct device *dev)
{
        return __adb_suspend(to_platform_device(dev), PMSG_HIBERNATE);
}

/*
 * reset bus after sleep
 */
static int __adb_resume(struct platform_device *dev)
{
        adb_got_sleep = 0;
        up(&adb_probe_mutex);
        adb_reset_bus();

        return 0;
}

static int adb_resume(struct device *dev)
{
        return __adb_resume(to_platform_device(dev));
}
#endif /* CONFIG_PM */

static int __init adb_init(void)
{
        struct adb_driver *driver;
        int i;

#ifdef CONFIG_PPC32
        if (!machine_is(chrp) && !machine_is(powermac))
                return 0;
#endif
#ifdef CONFIG_MAC
        if (!MACH_IS_MAC)
                return 0;
#endif

        /* xmon may do early-init */
        if (adb_inited)
                return 0;
        adb_inited = 1;
                
        adb_controller = NULL;

        i = 0;
        while ((driver = adb_driver_list[i++]) != NULL) {
                if (!driver->probe()) {
                        adb_controller = driver;
                        break;
                }
        }
        if (adb_controller != NULL && adb_controller->init &&
            adb_controller->init())
                adb_controller = NULL;
        if (adb_controller == NULL) {
                pr_warn("Warning: no ADB interface detected\n");
        } else {
#ifdef CONFIG_PPC
                if (of_machine_is_compatible("AAPL,PowerBook1998") ||
                        of_machine_is_compatible("PowerBook1,1"))
                        sleepy_trackpad = 1;
#endif /* CONFIG_PPC */

                adbdev_init();
                adb_reset_bus();
        }
        return 0;
}

device_initcall(adb_init);

static int
do_adb_reset_bus(void)
{
        int ret;
        
        if (adb_controller == NULL)
                return -ENXIO;
                
        if (adb_controller->autopoll)
                adb_controller->autopoll(0);

        blocking_notifier_call_chain(&adb_client_list,
                ADB_MSG_PRE_RESET, NULL);

        if (sleepy_trackpad) {
                /* Let the trackpad settle down */
                msleep(500);
        }

        mutex_lock(&adb_handler_mutex);
        write_lock_irq(&adb_handler_lock);
        memset(adb_handler, 0, sizeof(adb_handler));
        write_unlock_irq(&adb_handler_lock);

        /* That one is still a bit synchronous, oh well... */
        if (adb_controller->reset_bus)
                ret = adb_controller->reset_bus();
        else
                ret = 0;

        if (sleepy_trackpad) {
                /* Let the trackpad settle down */
                msleep(1500);
        }

        if (!ret) {
                autopoll_devs = adb_scan_bus();
                if (adb_controller->autopoll)
                        adb_controller->autopoll(autopoll_devs);
        }
        mutex_unlock(&adb_handler_mutex);

        blocking_notifier_call_chain(&adb_client_list,
                ADB_MSG_POST_RESET, NULL);
        
        return ret;
}

void
adb_poll(void)
{
        if ((adb_controller == NULL)||(adb_controller->poll == NULL))
                return;
        adb_controller->poll();
}
EXPORT_SYMBOL(adb_poll);

static void adb_sync_req_done(struct adb_request *req)
{
        struct completion *comp = req->arg;

        complete(comp);
}

int
adb_request(struct adb_request *req, void (*done)(struct adb_request *),
            int flags, int nbytes, ...)
{
        va_list list;
        int i;
        int rc;
        struct completion comp;

        if ((adb_controller == NULL) || (adb_controller->send_request == NULL))
                return -ENXIO;
        if (nbytes < 1)
                return -EINVAL;

        req->nbytes = nbytes+1;
        req->done = done;
        req->reply_expected = flags & ADBREQ_REPLY;
        req->data[0] = ADB_PACKET;
        va_start(list, nbytes);
        for (i = 0; i < nbytes; ++i)
                req->data[i+1] = va_arg(list, int);
        va_end(list);

        if (flags & ADBREQ_NOSEND)
                return 0;

        /* Synchronous requests block using an on-stack completion */
        if (flags & ADBREQ_SYNC) {
                WARN_ON(done);
                req->done = adb_sync_req_done;
                req->arg = &comp;
                init_completion(&comp);
        }

        rc = adb_controller->send_request(req, 0);

        if ((flags & ADBREQ_SYNC) && !rc && !req->complete)
                wait_for_completion(&comp);

        return rc;
}
EXPORT_SYMBOL(adb_request);

 /* Ultimately this should return the number of devices with
    the given default id.
    And it does it now ! Note: changed behaviour: This function
    will now register if default_id _and_ handler_id both match
    but handler_id can be left to 0 to match with default_id only.
    When handler_id is set, this function will try to adjust
    the handler_id id it doesn't match. */
int
adb_register(int default_id, int handler_id, struct adb_ids *ids,
             void (*handler)(unsigned char *, int, int))
{
        int i;

        mutex_lock(&adb_handler_mutex);
        ids->nids = 0;
        for (i = 1; i < 16; i++) {
                if ((adb_handler[i].original_address == default_id) &&
                    (!handler_id || (handler_id == adb_handler[i].handler_id) || 
                    try_handler_change(i, handler_id))) {
                        if (adb_handler[i].handler != 0) {
                                pr_err("Two handlers for ADB device %d\n",
                                       default_id);
                                continue;
                        }
                        write_lock_irq(&adb_handler_lock);
                        adb_handler[i].handler = handler;
                        write_unlock_irq(&adb_handler_lock);
                        ids->id[ids->nids++] = i;
                }
        }
        mutex_unlock(&adb_handler_mutex);
        return ids->nids;
}
EXPORT_SYMBOL(adb_register);

int
adb_unregister(int index)
{
        int ret = -ENODEV;

        mutex_lock(&adb_handler_mutex);
        write_lock_irq(&adb_handler_lock);
        if (adb_handler[index].handler) {
                while(adb_handler[index].busy) {
                        write_unlock_irq(&adb_handler_lock);
                        yield();
                        write_lock_irq(&adb_handler_lock);
                }
                ret = 0;
                adb_handler[index].handler = NULL;
        }
        write_unlock_irq(&adb_handler_lock);
        mutex_unlock(&adb_handler_mutex);
        return ret;
}
EXPORT_SYMBOL(adb_unregister);

void
adb_input(unsigned char *buf, int nb, int autopoll)
{
        int i, id;
        static int dump_adb_input;
        unsigned long flags;
        
        void (*handler)(unsigned char *, int, int);

        /* We skip keystrokes and mouse moves when the sleep process
         * has been started. We stop autopoll, but this is another security
         */
        if (adb_got_sleep)
                return;
                
        id = buf[0] >> 4;
        if (dump_adb_input) {
                pr_info("adb packet: ");
                for (i = 0; i < nb; ++i)
                        pr_cont(" %x", buf[i]);
                pr_cont(", id = %d\n", id);
        }
        write_lock_irqsave(&adb_handler_lock, flags);
        handler = adb_handler[id].handler;
        if (handler != NULL)
                adb_handler[id].busy = 1;
        write_unlock_irqrestore(&adb_handler_lock, flags);
        if (handler != NULL) {
                (*handler)(buf, nb, autopoll);
                wmb();
                adb_handler[id].busy = 0;
        }
                
}

/* Try to change handler to new_id. Will return 1 if successful. */
static int try_handler_change(int address, int new_id)
{
        struct adb_request req;

        if (adb_handler[address].handler_id == new_id)
            return 1;
        adb_request(&req, NULL, ADBREQ_SYNC, 3,
            ADB_WRITEREG(address, 3), address | 0x20, new_id);
        adb_request(&req, NULL, ADBREQ_SYNC | ADBREQ_REPLY, 1,
            ADB_READREG(address, 3));
        if (req.reply_len < 2)
            return 0;
        if (req.reply[2] != new_id)
            return 0;
        adb_handler[address].handler_id = req.reply[2];

        return 1;
}

int
adb_try_handler_change(int address, int new_id)
{
        int ret;

        mutex_lock(&adb_handler_mutex);
        ret = try_handler_change(address, new_id);
        mutex_unlock(&adb_handler_mutex);
        if (ret)
                pr_debug("adb handler change: [%d] 0x%X\n", address, new_id);
        return ret;
}
EXPORT_SYMBOL(adb_try_handler_change);

int
adb_get_infos(int address, int *original_address, int *handler_id)
{
        mutex_lock(&adb_handler_mutex);
        *original_address = adb_handler[address].original_address;
        *handler_id = adb_handler[address].handler_id;
        mutex_unlock(&adb_handler_mutex);

        return (*original_address != 0);
}


/*
 * /dev/adb device driver.
 */

#define ADB_MAJOR       56      /* major number for /dev/adb */

struct adbdev_state {
        spinlock_t      lock;
        atomic_t        n_pending;
        struct adb_request *completed;
        wait_queue_head_t wait_queue;
        int             inuse;
};

static void adb_write_done(struct adb_request *req)
{
        struct adbdev_state *state = (struct adbdev_state *) req->arg;
        unsigned long flags;

        if (!req->complete) {
                req->reply_len = 0;
                req->complete = 1;
        }
        spin_lock_irqsave(&state->lock, flags);
        atomic_dec(&state->n_pending);
        if (!state->inuse) {
                kfree(req);
                if (atomic_read(&state->n_pending) == 0) {
                        spin_unlock_irqrestore(&state->lock, flags);
                        kfree(state);
                        return;
                }
        } else {
                struct adb_request **ap = &state->completed;
                while (*ap != NULL)
                        ap = &(*ap)->next;
                req->next = NULL;
                *ap = req;
                wake_up_interruptible(&state->wait_queue);
        }
        spin_unlock_irqrestore(&state->lock, flags);
}

static int
do_adb_query(struct adb_request *req)
{
        int     ret = -EINVAL;

        switch(req->data[1]) {
        case ADB_QUERY_GETDEVINFO:
                if (req->nbytes < 3)
                        break;
                mutex_lock(&adb_handler_mutex);
                req->reply[0] = adb_handler[req->data[2]].original_address;
                req->reply[1] = adb_handler[req->data[2]].handler_id;
                mutex_unlock(&adb_handler_mutex);
                req->complete = 1;
                req->reply_len = 2;
                adb_write_done(req);
                ret = 0;
                break;
        }
        return ret;
}

static int adb_open(struct inode *inode, struct file *file)
{
        struct adbdev_state *state;
        int ret = 0;

        mutex_lock(&adb_mutex);
        if (iminor(inode) > 0 || adb_controller == NULL) {
                ret = -ENXIO;
                goto out;
        }
        state = kmalloc(sizeof(struct adbdev_state), GFP_KERNEL);
        if (state == 0) {
                ret = -ENOMEM;
                goto out;
        }
        file->private_data = state;
        spin_lock_init(&state->lock);
        atomic_set(&state->n_pending, 0);
        state->completed = NULL;
        init_waitqueue_head(&state->wait_queue);
        state->inuse = 1;

out:
        mutex_unlock(&adb_mutex);
        return ret;
}

static int adb_release(struct inode *inode, struct file *file)
{
        struct adbdev_state *state = file->private_data;
        unsigned long flags;

        mutex_lock(&adb_mutex);
        if (state) {
                file->private_data = NULL;
                spin_lock_irqsave(&state->lock, flags);
                if (atomic_read(&state->n_pending) == 0
                    && state->completed == NULL) {
                        spin_unlock_irqrestore(&state->lock, flags);
                        kfree(state);
                } else {
                        state->inuse = 0;
                        spin_unlock_irqrestore(&state->lock, flags);
                }
        }
        mutex_unlock(&adb_mutex);
        return 0;
}

static ssize_t adb_read(struct file *file, char __user *buf,
                        size_t count, loff_t *ppos)
{
        int ret = 0;
        struct adbdev_state *state = file->private_data;
        struct adb_request *req;
        DECLARE_WAITQUEUE(wait, current);
        unsigned long flags;

        if (count < 2)
                return -EINVAL;
        if (count > sizeof(req->reply))
                count = sizeof(req->reply);

        req = NULL;
        spin_lock_irqsave(&state->lock, flags);
        add_wait_queue(&state->wait_queue, &wait);
        set_current_state(TASK_INTERRUPTIBLE);

        for (;;) {
                req = state->completed;
                if (req != NULL)
                        state->completed = req->next;
                else if (atomic_read(&state->n_pending) == 0)
                        ret = -EIO;
                if (req != NULL || ret != 0)
                        break;
                
                if (file->f_flags & O_NONBLOCK) {
                        ret = -EAGAIN;
                        break;
                }
                if (signal_pending(current)) {
                        ret = -ERESTARTSYS;
                        break;
                }
                spin_unlock_irqrestore(&state->lock, flags);
                schedule();
                spin_lock_irqsave(&state->lock, flags);
        }

        set_current_state(TASK_RUNNING);
        remove_wait_queue(&state->wait_queue, &wait);
        spin_unlock_irqrestore(&state->lock, flags);
        
        if (ret)
                return ret;

        ret = req->reply_len;
        if (ret > count)
                ret = count;
        if (ret > 0 && copy_to_user(buf, req->reply, ret))
                ret = -EFAULT;

        kfree(req);
        return ret;
}

static ssize_t adb_write(struct file *file, const char __user *buf,
                         size_t count, loff_t *ppos)
{
        int ret/*, i*/;
        struct adbdev_state *state = file->private_data;
        struct adb_request *req;

        if (count < 2 || count > sizeof(req->data))
                return -EINVAL;
        if (adb_controller == NULL)
                return -ENXIO;

        req = kmalloc(sizeof(struct adb_request),
                                             GFP_KERNEL);
        if (req == NULL)
                return -ENOMEM;

        req->nbytes = count;
        req->done = adb_write_done;
        req->arg = (void *) state;
        req->complete = 0;
        
        ret = -EFAULT;
        if (copy_from_user(req->data, buf, count))
                goto out;

        atomic_inc(&state->n_pending);

        /* If a probe is in progress or we are sleeping, wait for it to complete */
        down(&adb_probe_mutex);

        /* Queries are special requests sent to the ADB driver itself */
        if (req->data[0] == ADB_QUERY) {
                if (count > 1)
                        ret = do_adb_query(req);
                else
                        ret = -EINVAL;
                up(&adb_probe_mutex);
        }
        /* Special case for ADB_BUSRESET request, all others are sent to
           the controller */
        else if ((req->data[0] == ADB_PACKET) && (count > 1)
                && (req->data[1] == ADB_BUSRESET)) {
                ret = do_adb_reset_bus();
                up(&adb_probe_mutex);
                atomic_dec(&state->n_pending);
                if (ret == 0)
                        ret = count;
                goto out;
        } else {        
                req->reply_expected = ((req->data[1] & 0xc) == 0xc);
                if (adb_controller && adb_controller->send_request)
                        ret = adb_controller->send_request(req, 0);
                else
                        ret = -ENXIO;
                up(&adb_probe_mutex);
        }

        if (ret != 0) {
                atomic_dec(&state->n_pending);
                goto out;
        }
        return count;

out:
        kfree(req);
        return ret;
}

static const struct file_operations adb_fops = {
        .owner          = THIS_MODULE,
        .llseek         = no_llseek,
        .read           = adb_read,
        .write          = adb_write,
        .open           = adb_open,
        .release        = adb_release,
};

#ifdef CONFIG_PM
static const struct dev_pm_ops adb_dev_pm_ops = {
        .suspend = adb_suspend,
        .resume = adb_resume,
        /* Hibernate hooks */
        .freeze = adb_freeze,
        .thaw = adb_resume,
        .poweroff = adb_poweroff,
        .restore = adb_resume,
};
#endif

static struct platform_driver adb_pfdrv = {
        .driver = {
                .name = "adb",
#ifdef CONFIG_PM
                .pm = &adb_dev_pm_ops,
#endif
        },
};

static struct platform_device adb_pfdev = {
        .name = "adb",
};

static int __init
adb_dummy_probe(struct platform_device *dev)
{
        if (dev == &adb_pfdev)
                return 0;
        return -ENODEV;
}

static void __init
adbdev_init(void)
{
        if (register_chrdev(ADB_MAJOR, "adb", &adb_fops)) {
                pr_err("adb: unable to get major %d\n", ADB_MAJOR);
                return;
        }

        adb_dev_class = class_create(THIS_MODULE, "adb");
        if (IS_ERR(adb_dev_class))
                return;
        device_create(adb_dev_class, NULL, MKDEV(ADB_MAJOR, 0), NULL, "adb");

        platform_device_register(&adb_pfdev);
        platform_driver_probe(&adb_pfdrv, adb_dummy_probe);
}